Speedometer-type chart with negative values

Hello,

I am trying to make a speedometer/gauge-chart which has 2 sections, red (negative) and green (positive). When value is 0, the pointer should be between them, like in my attachment. I would like the range to be -100...+100, but I'm having trouble with negative values, and stuff in general. Currently the meter maxes at value 50, I would like it to max at 100. Vice versa, lowest value on the meter should be at value -100.

Any help would be highly appreciated!

Extra kudos if you manage to make it like this (outer ring showing values):

nicemeter.png